1. Field of the Invention
This invention relates to a method and apparatus for making a vehicle axle.
2. Description of the Prior Art
Axles for vehicles have previously been manufactured from tubular blanks with ends that are formed so as to be capable of supporting associated wheels. One type of axle end supports a king pin used to pivotally mount a wheel spindle about an axis around which the wheel is turned. Another type of axle is made from a two piece construction including upper and lower members that are stamped and welded to each other with associated projections thereof at an end of the axle provided for mounting ball joints that support the wheel spindle. This latter type of axle has a bifurcated end shape where stress concentration can occur at the welds between the two members.
In manufacturing vehicle axles from tubular blanks of a uniform wall thickness, sometimes the combined height and width of the axle required for strength at certain locations is greater than the combined height and width that can be utilized at other locations without interference between the axle and other vehicle components during axle movement.
Of course, axles have also been made of a solid construction in addition to hollow axles that are made from either a tubular or two piece construction as described above. Solid axles are usually made by a forging process and necessarily have a smaller strength to weight ratio than hollow axles since more material of the axle is located adjacent the neutral axes of twisting and bending than is the case with hollow axles. U.S. Patents relating to axles are as follows; U.S. Pat. Nos. 2,007,793; 2,053,975; 2,124,406; 2,752,673; 2,911,264; and 3,804,467.